Orderfile: Simple call-graph-based orderfile.

This CL adds simple function call graph clustering. The call graph is
inferred from the function ordering offset list, and the orderfile is
produced by clustering based on this inferred call graph.

In local testing, this change recovers the speedometer performance
lost in the bug. Startup is not affected, and memory shows similar
improvement to the original system_health orderfile.

Bug: 894827
Change-Id: Iedab652d0f25c9c9ea481c2a75214cac41dee368
Reviewed-on: https://chromium-review.googlesource.com/c/1350876
Commit-Queue: Matthew Cary <mattcary@chromium.org>
Reviewed-by: Benoit L <lizeb@chromium.org>
Reviewed-by: Egor Pasko <pasko@chromium.org>
Cr-Commit-Position: refs/heads/master@{#612644}

diff --git a/tools/cygprofile/orderfile_generator_backend.py b/tools/cygprofile/orderfile_generator_backend.py
index 12d7091..54d5a34d 100755
--- a/tools/cygprofile/orderfile_generator_backend.py
+++ b/tools/cygprofile/orderfile_generator_backend.py

@@ -27,10 +27,10 @@
 import tempfile
 import time
 
+import cluster
 import cyglog_to_orderfile
 import cygprofile_utils
 import patch_orderfile
-import phased_orderfile
 import process_profiles
 import profile_android_startup
 import symbol_extractor
@@ -527,25 +527,11 @@
     profiles = process_profiles.ProfileManager(files)
     processor = process_profiles.SymbolOffsetProcessor(
         self._compiler.lib_chrome_so)
-    phaser = phased_orderfile.PhasedAnalyzer(profiles, processor)
-    if self._options.offsets_for_memory:
-      profile_offsets = phaser.GetOffsetsForMemoryFootprint()
-    else:
-      profile_offsets = phaser.GetOffsetsForStartup()
-    self._output_data['orderfile_size'] = {
-        'startup_kib': processor.OffsetsPrimarySize(
-            profile_offsets.startup) / 1024,
-        'common_kib': processor.OffsetsPrimarySize(
-            profile_offsets.common) / 1024,
-        'interaction_kib': processor.OffsetsPrimarySize(
-            profile_offsets.interaction) / 1024}
-
-    offsets_list = (profile_offsets.startup +
-                    profile_offsets.common +
-                    profile_offsets.interaction)
-    ordered_symbols = processor.GetOrderedSymbols(offsets_list)
+    ordered_symbols= cluster.ClusterOffsets(profiles, processor)
     if not ordered_symbols:
       raise Exception('Failed to get ordered symbols')
+    self._output_data['offsets_kib'] = processor.SymbolsSize(
+            ordered_symbols) / 1024
     with open(self._GetUnpatchedOrderfileFilename(), 'w') as orderfile:
       orderfile.write('\n'.join(ordered_symbols))
 
@@ -654,7 +640,7 @@
     Args:
       filename: (str) Orderfile to upload.
     """
-    # First compute hashes so that we can download them later if we need to
+    # First compute hashes so that we can download them later if we need to.
     self._step_recorder.BeginStep('Compute hash for ' + filename)
     self._RecordHash(filename)
     if self._options.buildbot:
@@ -830,10 +816,6 @@
   parser.add_argument('--monochrome', action='store_true',
                       help=('Compile and instrument monochrome (for post-N '
                             'devices).'))
-  parser.add_argument('--offsets-for-memory', action='store_true',
-                      help=('Favor memory savings in the orderfile. Used '
-                            'with --system-health-orderfile.'),
-                      default=False)
 
   parser.add_argument('--manual-symbol-offsets', default=None, type=str,
                       help=('File of list of ordered symbol offsets generated '